Basin-wide variation in tree hydraulic safety margins predicts the carbon balance of Amazon forests

Tropical forests face increasing climate risk1,2, yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, Ψ50) and hydraulic safety margins (for example, HSM50) are important predictors of drought-induced mortality risk3–5, little is known about how these vary across Earth’s largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters Ψ50 and HSM50 vary markedly across the Amazon and are related to average long-term rainfall characteristics. Both Ψ50 and HSM50 influence the biogeographical distribution of Amazon tree species. However, HSM50 was the only significant predictor of observed decadal-scale changes in forest biomass. Old-growth forests with wide HSM50 are gaining more biomass than are low HSM50 forests. We propose that this may be associated with a growth–mortality trade-off whereby trees in forests consisting of fast-growing species take greater hydraulic risks and face greater mortality risk. Moreover, in regions of more pronounced climatic change, we find evidence that forests are losing biomass, suggesting that species in these regions may be operating beyond their hydraulic limits. Continued climate change is likely to further reduce HSM50 in the Amazon6,7, with strong implications for the Amazon carbon sink

Basin-wide variation in tree hydraulic safety margins predicts the carbon balance of Amazon forests

This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: The pan-Amazonian HT dataset (Ψ 50, Ψ dry and HSM50) and branch wood density per species per site, as well as forest dynamic and climate data per plot presented in this study are available as a ForestPlots.net data package at https://forestplots.net/data-packages/Tavares-et-al-2023. Basal area weighted mean LMA is shown in Supplementary Table 2. Species stem wood density data were obtained from Global Wood Density database65,66. Species WDA data were extracted from ref. 45.Code availability: The codes to recreate the main analyses and the main figures presented in this study are available as a ForestPlots.net data package at https://forestplots.net/data-packages/Tavares-et-al-2023.Tropical forests face increasing climate risk, yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, Ψ 50) and hydraulic safety margins (for example, HSM50) are important predictors of drought-induced mortality risk, little is known about how these vary across Earth’s largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters Ψ 50 and HSM50 vary markedly across the Amazon and are related to average long-term rainfall characteristics. Both Ψ 50 and HSM50 influence the biogeographical distribution of Amazon tree species. However, HSM50 was the only significant predictor of observed decadal-scale changes in forest biomass. Old-growth forests with wide HSM50 are gaining more biomass than are low HSM50 forests. We propose that this may be associated with a growth–mortality trade-off whereby trees in forests consisting of fast-growing species take greater hydraulic risks and face greater mortality risk. Moreover, in regions of more pronounced climatic change, we find evidence that forests are losing biomass, suggesting that species in these regions may be operating beyond their hydraulic limits. Continued climate change is likely to further reduce HSM50 in the Amazon, with strong implications for the Amazon carbon sink

Bacteriological investigation of microorganisms (Salmonella sp. and other Enterobacteriaceae) in common quails (Coturnix coturnix) submitted to different forced-molting procedures

The aim of this study was to investigate the presence of Salmonella in common quails submitted to forced molting. A total of 240 quails were divided at 40 weeks of age into four groups: CG (control, quails not submitted to molting); FM (fasting method); WM (fed wheat midds ad libitum); and ZM (zinc oxide method). From each group, 10 cloacal swabs, 10 fecal samples, and 20 egg samples were collected before molting (two weeks) and after molting (two weeks). The microbiological procedures for Salmonella spp. identification were performed in four steps. The agglutination test, using somatic and flagellar antigens, was used to confirm Salmonella-suspected colonies. According to the methodology applied, none of the samples was positive for Salmonella spp. The results showed that 20.0% of the egg samples from birds submitted to forced molting were contaminated with enterobacteria. It was concluded that, under the conditions of the present experiment, the stress caused by forced molting did not induce infection by Salmonella spp. or increased Enterobacteriaceae contamination levels in the eggs

Effect of associated vaccines on the interference between Newcastle disease virus and infectious bronchitis virus in broilers

The phenomenon of viral interference between live vaccines against Newcastle Disease and infectious bronchitis has been reported since the 50's and many researchers have reported its prejudicial effects on avian immunization. Therefore, this study evaluated the effect of associated vaccines on the interference between Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) in broilers. There were 400 broiler chicks divided into five groups. The groups were submitted to mono or polyvalent vaccinations against IBV and NDV, except for the non-vaccinated control group (CG). Sera were collected at 35 and 45 days of age and submitted to serologic tests to assess antibody levels. It was observed the occurrence of interference in the immune response against NDV by the use of associated vaccines to NDV and IBV; however, the group that was immunized with commercial combined vaccines (IBV+NDV) presented antibody titers to NDV similar to the group that was given only vaccine against NDV. We concluded based on these preliminary studies that the interference of IBV on the immune response against NDV depends also whether the association between the two vaccines is done just before vaccination or in the manufacturing laboratory

Salmonella Gallinarum virulence in experimentally-infected Japanese quails (Coturnix japonica)

Salmonella Gallinarum is the agent of fowl typhoid in poultry and infects mainly adult galliforms, causing significant economic losses in poultry production. Because quails are susceptible to this disease and quail production is becoming increasingly important in Brazil, this study was carried out to evaluate the virulence of Salmonella Gallinarum strain to quails. The inoculum was prepared from S. Gallinarum strain resistant to nalidixic acid. Forty eight 16-week-old Japanese quails were randomly distributed in three groups. Before the experiment, cloacal swabs were collected from all birds in order to confirm they were free from Salmonella spp. Cloacal swabs and fecal samples were collected on days 03, 06, 09, 12, and 15 post-inoculation. Birds that died during the experiment were submitted to post-mortem examination, and had their organs aseptically collected for bacteriological examination. All eggs produced during the experiment were also examined. The mortality rate recorded during the experiment was 43.75% (21/48). S. Gallinarum was recovered from the organs of the birds that naturally died during the experiment, but the agent was not isolated from the organs of sacrificed birds. No egg sample was positive for Salmonella Gallinarum. It was concluded that S. Gallinarum may be recovered from the organs of experimentally-infected Japanese quails

Dissemination of Salmonella enteritidis by experimentally-infected pigeons

Two groups of domestic pigeons (Columba livia) were experimentally infected orally with doses of 9.5 x10(7) and 9.5 x10(9) CFU/mL (group A and B, respectively) of a Salmonella Enteritidis (SE) strain isolated from chickens. None of the used doses caused mortality of the inoculated birds; however, the pathogen was successfully recovered from the liver and spleen of group B birds on day 7 post-inoculation (dpi). Pathogen shedding, as evaluated through cloacal swabs, occurred in both groups until the 14th day of observation (p <0.05). Among all fecal samples collected from group B (n=4), three different birds shed the pathogen in their feces, out of which two were positive on 3 dpi and one on 7 dpi. The same number of fecal samples was evaluated in group A and only one bird shed the pathogen, on 7 and 14 dpi. The concentration of the microorganism in the feces was lower in group A than any sample from Group B. Salmonella Enteritidis isolated from chickens, when inoculated in pigeons, may be recovered from feces, cloacal swabs and organs, and these birds may contaminate poultry causing economic losses as well as posing a risk to the public health

Isolation and Antimicrobial Resistance Profiles of Enterobacteria from Nestling Grey-Breasted Parakeets (Pyrrhura Griseipectus)

ABSTRACT The psittacine Pyrrhura griseipectus is a threatened species currently only found in Ceará State, Brazil. A microbiological survey was conducted to determine the composition of the enteric microbiota of this species, as well as the phenotypic profiles of antimicrobial susceptibility presented by the isolates. Cloacal swabs were collected from individual birds and submitted to microbiological processing. Antimicrobial susceptibility profiles were evaluated using the disk diffusion method. Bacteria of the genus Escherichia, Proteus, Citrobacter, Pantoea, Klebsiella, Enterobacter, Morganella, Hafnia, Enterobacter, and Serratia were isolated. The most frequently isolated species were Escherichia coli, Proteus mirabilis and Proteus vulgaris, corresponding to 36.1%, 26.4%, and 8.3%, respectively. Isolates were more frequently resistant to azithromycin and tetracycline, while Escherichia coli was the main species presenting multidrug resistance. In conclusion, free-living grey-breasted parakeets may harbor enterobacteria with high antimicrobial resistance rates